1124 Raffle for Weibo Followers (20分)

最新推荐文章于 2021-12-08 20:07:29 发布

原创最新推荐文章于 2021-12-08 20:07:29 发布 · 96 阅读

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本文介绍了一个抽奖算法的实现，该算法用于从微博转发者中按特定间隔选择幸运儿，避免重复中奖，确保每位参与者都有公平的机会。代码示例使用C++实现，展示了如何通过跳过已中奖的参与者来维护抽奖的公正性。

John got a full mark on PAT. He was so happy that he decided to hold a raffle（抽奖） for his followers on Weibo -- that is, he would select winners from every N followers who forwarded his post, and give away gifts. Now you are supposed to help him generate the list of winners.

Input Specification:

Each input file contains one test case. For each case, the first line gives three positive integers M (≤ 1000), N and S, being the total number of forwards, the skip number of winners, and the index of the first winner (the indices start from 1). Then M lines follow, each gives the nickname (a nonempty string of no more than 20 characters, with no white space or return) of a follower who has forwarded John's post.

Note: it is possible that someone would forward more than once, but no one can win more than once. Hence if the current candidate of a winner has won before, we must skip him/her and consider the next one.

Output Specification:

For each case, print the list of winners in the same order as in the input, each nickname occupies a line. If there is no winner yet, print Keep going... instead.

Sample Input 1:

9 3 2
Imgonnawin!
PickMe
PickMeMeMeee
LookHere
Imgonnawin!
TryAgainAgain
TryAgainAgain
Imgonnawin!
TryAgainAgain

Sample Output 1:

PickMe
Imgonnawin!
TryAgainAgain

Sample Input 2:

2 3 5
Imgonnawin!
PickMe

Sample Output 2:

Keep going...

#include<iostream>

#include<algorithm>
#include<vector>
#include<unordered_set>
using namespace std;

int main(){

    int m, n , s;
    cin >> m >> n >> s;
    vector<string> vec(m + 1);
    unordered_set<string> un_set;
    for(int i = 1; i <= m; i++){
        
        cin >> vec[i];

    }
    int index = s;
    if(s > m){

        cout << "Keep going..." << endl;


    }else
    {
        while (index <= m)
        {
            if(un_set.find(vec[index]) == un_set.end()){
            
                un_set.insert(vec[index]);
                cout << vec[index] << endl;

            }else
            {
                while (un_set.find(vec[index]) != un_set.end())
                {
                    index++;
                    // cout << index << "====" << endl;
                }
                if(index <= m){

                    un_set.insert(vec[index]);
                    cout << vec[index] << endl;
                }

                
            
            }

            index = index + n;
        
        

        }
    }
    
    
    
    



    return 0;
}